The inking system of a printing machine generally comprises a rotating doctor roller which picks up ink on its surface from a supply ink fountain. A uniform ink film is formed on the roller by means of an adjustable blade. The ink is transferred from the doctor roller to the ink feed roller and transferred into the inking roller system.
In the devices presently used, the doctor roller rotates continuously or intermittently. The amount of ink transferred to the ink feed roller from the continuously rotating doctor roller depends on the length of mutual rolling path of both rollers. In the devices having an intermittently rotating doctor roller, the amount of ink transferred to the ink feed roller depends on the angle of rotation and contact of the doctor roller which is generally adjustable.
In the devices which are provided with a continuously rotating doctor roller, the amount of ink supplied to the inking system is regulated by the length of rolling contact of the doctor roller with the ink feed roller which is controlled by a regulation element. The amount of ink supplied to the inking system cannot be changed without readjustment of the regulation element.